1. Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Boston, MA 02115, USA.
2. Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115, USA.
3. Department of Anatomy and Developmental Biology, Monash University, Clayton, Victoria 3800, Australia.
4. School of Immunity and Infection, University of Birmingham, Birmingham B15 2TT, UK.
5. Center for Engineering in Medicine and Surgical Services, Massachusetts General Hospital, Harvard Medical School, and Shriners Hospitals for Children, Boston, MA 02114, USA.
6. Harvard Stem Cell Institute, Cambridge, MA 02138, USA.